php form embedding php code in web page

1. Add PHP scripts in HTML tags

In the process of Web coding, PHP is an embedded language that can be mixed with HTML. Feel free to add the PHP script tag to your HTML. All text between the two tags will be interpreted as PHP, and any text outside the tag will be considered normal. HTML.

For example, add the PHP identifier in the tag and use the include statement to reference the external file index.php. The code is as follows:

<?php
    include(" index.php ");       //引入外部文件
?>

However, among thousands of codes, how to distinguish HTML and PHP? PHP decomposition tags (tags) are like boundary stones, accurately marking the start and end positions of PHP scripts. There are four decomposers that allow PHP to be embedded in HTML.

(1): PhP standard decomposers.

(2): abbreviated decomposition symbols.

(3): JavaScript/VBScript style decomposer

(4)<% and %>: ASP Decomposer.

The first and second methods are the most commonly used; the third method is similar to the JavaScript embedding method; the fourth method is similar to the ASP embedding method.

Note: If you want to use PHP to support the <%%> method, you need to make the following settings in the configuration file PHP.ini:

short_open_tag = on;

asp_tags = on;

Between a pair of decomposers "<" and ">" The content is all PHP code, and the other content is HTML elements.

Terminator of PHP statement

The terminator of PHP statement is a semicolon ";", that is, after each sentence of PHP code, ";" needs to be added to indicate the end of the statement.

PHP is case-sensitive and ignores spaces, tabs, and carriage returns in statements. This allows the program to have a good indentation style.

2. Assign the value attribute of the form element

In the process of web development, it is usually necessary to assign the value attribute of the form element. Assign a value to get the default value of this form element. For example, to assign a value to a hidden field of a form element, you only need to add the assigned value to the value attribute. The code example is as follows:

<?php
   $hidden="abc001"                          // 为变量 $hidden 赋值
?>

The value of the hidden field:

<input type="hidden" name="id" value="<?php echo $hidden;?>">

As can be seen from the above code, the variable $hidden is first assigned an initial value, and then the value of the variable $hidden is assigned to the hidden field. In the process of program development, hidden fields are often used to store some information that does not need to be displayed or parameters that need to be transmitted.

Let’s briefly introduce what hidden fields are

Hidden fields are invisible elements used to collect or send information. For web pages Hidden fields are invisible to visitors. When the form is submitted, the hidden field will send information to the server with the name and value you defined when setting it up.

Advantages of hidden domains

1. No server resources are required.

　2. Wide support, any client supports hidden domains.

　3. The implementation is simple. The hidden field belongs to the HTML control and does not require programming knowledge like the server control.

　Disadvantages of hidden domains

　1. It has high security potential risks.

　2. The storage structure is simple.

　3. If more large values ​​are stored, it will cause performance problems.

　4. If there are too many hidden domains, they will be banned in some clients.

　5. Hidden fields store data on the server, not on the client.

Note that if the page has too many hidden fields during development, these hidden fields will be stored on the server. When the client browses the page, some firewalls will scan the page to ensure the security of the operating system. If the page has too many hidden fields, these firewalls may prohibit certain functions of the page.

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